Indole, indazole and benzimidazole arylamides as p2x3 and p2x2/3 antagonists

ABSTRACT

Compounds of the formula I: 
     
       
         
         
             
             
         
       
     
     or a pharmaceutically acceptable salt thereof, wherein, X, Y, Z, R 1 , R 2 , R 3 , R 4  and R 5  are as defined herein. Also disclosed are methods of using the compounds for treating diseases associated with P2X 3  and/or a P2X 2/3  receptor antagonists and methods of making the compounds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of U.S. provisional patentapplication Ser. No. 61/219,177 filed on Jun. 22, 2009, the disclosureof which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention pertains to compounds useful for treatment of diseasesassociated with P2X purinergic receptors, and more particularly to P2X₃and/or P2X_(2/3) antagonists usable for treatment of genitourinary,pain, inflammatory, gastrointestinal and respiratory diseases,conditions and disorders.

BACKGROUND OF THE INVENTION

The urinary bladder is responsible for two important physiologicalfunctions: urine storage and urine emptying. This process involves twomain steps: (1) the bladder fills progressively until the tension in itswalls rises above a threshold level; and (2) a nervous reflex, calledthe micturition reflex, occurs that empties the bladder or, if thisfails, at least causes a conscious desire to urinate. Although themicturition reflex is an autonomic spinal cord reflex, it can also beinhibited or mediated by centers in the cerebral cortex or brain.

Purines, acting via extracellular purinoreceptors, have been implicatedas having a variety of physiological and pathological roles. (See,Burnstock (1993) Drug Dev. Res. 28:195-206.) ATP, and to a lesserextent, adenosine, can stimulate sensory nerve endings resulting inintense pain and a pronounced increase in sensory nerve discharge. ATPreceptors have been classified into two major families, the P2Y- andP2X-purinoreceptors, on the basis of molecular structure, transductionmechanisms, and pharmacological characterization. TheP2Y-purinoreceptors are G-protein coupled receptors, while theP2X-purinoreceptors are a family of ATP-gated cation channels.Purinergic receptors, in particular, P2X receptors, are known to formhomomultimers or heteromultimers. To date, cDNAs for several P2Xreceptors subtypes have been cloned, including: six homomeric receptors,P2X₁; P2X₂; P2X₃; P2X₄; P2X₅; and P2X₇; and several heteromericreceptors P2X_(2/3), P2X_(4/6), P2X_(1/5) (See, e.g., Chen, et al.(1995) Nature 377:428-431; Lewis, et al. (1995) Nature 377:432-435; andBurnstock (1997) Neurophamacol. 36:1127-1139). The structure andchromosomal mapping of mouse genomic P2X₃ receptor subunit has also beendescribed (Souslova, et al. (1997) Gene 195:101-111). In vitro,co-expression of P2X₂ and P2X₃ receptor subunits is necessary to produceATP-gated currents with the properties seen in some sensory neurons(Lewis, et al. (1995) Nature 377:432-435).

P2X receptor subunits are found on afferents in rodent and human bladderurothelium. Data exists suggesting that ATP may be released fromepithelial/endothelial cells of the urinary bladder or other holloworgans as a result of distention (Burnstock (1999) J. Anatomy194:335-342; and Ferguson et al. (1997) J. Physiol. 505:503-511). ATPreleased in this manner may serve a role in conveying information tosensory neurons located in subepithelial components, e.g., suburotheliallamina propria (Namasivayam, et al. (1999) BJU Intl. 84:854-860). TheP2X receptors have been studied in a number of neurons, includingsensory, sympathetic, parasympathetic, mesenteric, and central neurons(Zhong, et al. (1998) Br. J. Pharmacol. 125:771-781). These studiesindicate that purinergic receptors play a role in afferentneurotransmission from the bladder, and that modulators of P2X receptorsare potentially useful in the treatment of bladder disorders and othergenitourinary diseases or conditions.

Recent evidence also suggests a role of endogenous ATP and purinergicreceptors in nociceptive responses in mice (Tsuda, et al. (1999) Br. J.Pharmacol. 128:1497-1504). ATP-induced activation of P2X receptors ondorsal root ganglion nerve terminals in the spinal cord has been shownto stimulate release of glutamate, a key neurotransmitter involved innociceptive signaling (Gu and MacDermott, Nature 389:749-753 (1997)).P2X₃ receptors have been identified on nociceptive neurons in the toothpulp (Cook et al., Nature 387:505-508 (1997)). ATP released from damagedcells may thus lead to pain by activating P2X₃ and/or P2X_(2/3)containing receptors on nociceptive sensory nerve endings. This isconsistent with the induction of pain by intradermally applied ATP inthe human blister-base model (Bleehen, Br J Pharmacol 62:573-577(1978)). P2X antagonists have been shown to be analgesic in animalmodels (Driessen and Starke, Naunyn Schmiedebergs Arch Pharmacol350:618-625 (1994)). This evidence suggests that P2X₂ and P2X₃ areinvolved in nociception, and that modulators of P2X receptors arepotentially useful as analgesics.

Other researchers have shown that P2X₃ receptors are expressed in humancolon, and are expressed at higher levels in inflamed colon than innormal colon (Y. Yiangou et al, Neurogastroenterol Mot (2001)13:365-69). Other researchers have implicated the P2X₃ receptor indetection of distension or intraluminal pressure in the intestine, andinitiation of reflex contractions (X. Bian et al., J Physiol (2003)551.1:309-22), and have linked this to colitis (G. Wynn et al., Am JPhysiol Gastrointest Liver Physiol (2004) 287:G647-57).

Inge Brouns et al. (Am J Respir Cell Mol Biol (2000) 23:52-61) foundthat P2X₃ receptors are expressed in pulmonary neuroepithelial bodies(NEBs), implicating the receptor in pain transmission in the lung. Morerecently, others have implicated P2X₂ and P2X₃ receptors in pO₂detection in pulmonary NEBs (W. Rong et al., J Neurosci (2003)23(36):11315-21) and cough.

There is accordingly a need for compounds that act as modulators of P2Xreceptors, including antagonists of P2X₃ and P2X_(2/3) receptors, aswell as a need for methods of treating diseases, conditions anddisorders mediated by P2X₃ and/or P2X_(2/3) receptors. The presentinvention satisfies these needs as well as others.

SUMMARY OF THE INVENTION

The invention provides compounds of the formula I:

or pharmaceutically acceptable salts thereof,wherein:

R¹ is: C₁₋₆alkyl; or halo;

R² is: C₃₋₆cycloalkyl; C₁₋₆alkoxy-C₁₋₆alkyl; hydroxy-C₁₋₆alkyl; orheteroaryl-C₁₋₆alkyl;

R³ is: C₁₋₆alkyl; hydroxy-C₁₋₆alkyl; C₁₋₆alkoxy-C₁₋₆alkyl;halo-C₁₋₆alkyl; C₃₋₆cycloalkyl; C₃₋₆cycloalkyl-C₁₋₆alkyl; phenyloptionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl; or phenyl-C₁₋₆alkyl wherein the phenyl portion thereofis optionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl;

R⁴ and R⁵ each independently is: hydrogen; or fluoro;

X is: N; or CR^(a) wherein R^(a) is C₁₋₆alkyl or halo;

Y is: N; or CR^(b) wherein R^(b) is hydrogen or C₁₋₆alkyl; and

Z is: N; or CR^(c); wherein R^(c) is hydrogen or C₁₋₆alkyl.

The invention also provides and pharmaceutical compositions comprisingthe compounds, methods of using the compounds, and methods of preparingthe compounds.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Unless otherwise stated, the following terms used in this application,including the specification and claims, have the definitions givenbelow. It must be noted that, as used in the specification and theappended claims, the singular forms “a”, “an,” and “the” include pluralreferents unless the context clearly dictates otherwise.

“Agonist” refers to a compound that enhances the activity of anothercompound or receptor site.

“Alkyl” means the monovalent linear or branched saturated hydrocarbonmoiety, consisting solely of carbon and hydrogen atoms, having from oneto twelve carbon atoms. “Lower alkyl” refers to an alkyl group of one tosix carbon atoms, i.e. C₁-C₆alkyl. Examples of alkyl groups include, butare not limited to, methyl, ethyl, propyl, isopropyl, isobutyl,sec-butyl, tert-butyl, pentyl, n-hexyl, octyl, dodecyl, and the like.

“Alkenyl” means a linear monovalent hydrocarbon radical of two to sixcarbon atoms or a branched monovalent hydrocarbon radical of three tosix carbon atoms, containing at least one double bond, e.g., ethenyl,propenyl, and the like.

“Alkynyl” means a linear monovalent hydrocarbon radical of two to sixcarbon atoms or a branched monovalent hydrocarbon radical of three tosix carbon atoms, containing at least one triple bond, e.g., ethynyl,propynyl, and the like.

“Alkylene” means a linear saturated divalent hydrocarbon radical of oneto six carbon atoms or a branched saturated divalent hydrocarbon radicalof three to six carbon atoms, e.g., methylene, ethylene,2,2-dimethylethylene, propylene, 2-methylpropylene, butylene, pentylene,and the like.

“Alkoxy” and “alkyloxy”, which may be used interchangeably, mean amoiety of the formula —OR, wherein R is an alkyl moiety as definedherein. Examples of alkoxy moieties include, but are not limited to,methoxy, ethoxy, isopropoxy, and the like.

“Alkoxyalkyl” means a moiety of the formula R^(a)—O—R^(b)—, where R^(a)is alkyl and R^(b) is alkylene as defined herein. Exemplary alkoxyalkylgroups include, by way of example, 2-methoxyethyl, 3-methoxypropyl,1-methyl-2-methoxyethyl, 1-(2-methoxyethyl)-3-methoxypropyl, and1-(2-methoxyethyl)-3-methoxypropyl.

“Alkylcarbonyl” means a moiety of the formula —R′—R″, where R′ is oxoand R″ is alkyl as defined herein.

“Alkylsulfonyl” means a moiety of the formula —R′—R″, where R′ is —SO₂—and R″ is alkyl as defined herein.

“Alkylsulfonylalkyl means a moiety of the formula —R′—R″—R″″ where whereR′ is alkylene, R″ is —SO₂— and R″″ is alkyl as defined herein.

“Amino means a moiety of the formula —NRR′ wherein R and R′ eachindependently is hydrogen or alkyl as defined herein. “Amino thusincludes “alkylamino (where one of R and R′ is alkyl and the other ishydrogen) and “dialkylamino (where R and R′ are both alkyl.

“Alkoxyamino” means a moiety of the formula —NR—OR′ wherein R ishydrogen or alkyl and R′ is alkyl as defined herein.

“Alkylsulfanyl” means a moiety of the formula —SR wherein R is alkyl asdefined herein.

“Aminoalkyl” means a group —R—R′ wherein R′ is amino and R is alkyleneas defined herein. “Aminoalkyl” includes aminomethyl, aminoethyl,1-aminopropyl, 2-aminopropyl, and the like. The amino moiety of“aminoalkyl” may be substituted once or twice with alkyl to provide“alkylaminoalkyl” and “dialkylaminoalkyl” respectively.“Alkylaminoalkyl” includes methylaminomethyl, methylaminoethyl,methylaminopropyl, ethylaminoethyl and the like. “Dialkylaminoalkyl”includes dimethylaminomethyl, dimethylaminoethyl, dimethylaminopropyl,N-methyl-N-ethylaminoethyl, and the like.

“Aminoalkoxy” means a group —OR—R′ wherein R′ is amino and R is alkyleneas defined herein.

“Alkylsulfonylamido” means a moiety of the formula —NR′SO₂—R wherein Ris alkyl and R′ is hydrogen or alkyl.

“Aminocarbonyloxyalkyl” or “carbamylalkyl” means a group of the formula—R—O—C(O)—NR′R″ wherein R is alkylene and R′, R″ each independently ishydrogen or alkyl as defined herein.

“Alkynylalkoxy” means a group of the formula —O—R—R′ wherein R isalkylene and R′ is alkynyl as defined herein.

“Antagonist” refers to a compound that diminishes or prevents the actionof another compound or receptor site.

“Aryl” means a monovalent cyclic aromatic hydrocarbon moiety consistingof a mono-, bi- or tricyclic aromatic ring. The aryl group can beoptionally substituted as defined herein. Examples of aryl moietiesinclude, but are not limited to, phenyl, naphthyl, phenanthryl,fluorenyl, indenyl, pentalenyl, azulenyl, oxydiphenyl, biphenyl,methylenediphenyl, aminodiphenyl, diphenylsulfidyl, diphenylsulfonyl,diphenylisopropylidenyl, benzodioxanyl, benzofuranyl, benzodioxylyl,benzopyranyl, benzoxazinyl, benzoxazinonyl, benzopiperadinyl,benzopiperazinyl, benzopyrrolidinyl, benzomorpholinyl,methylenedioxyphenyl, ethylenedioxyphenyl, and the like, includingpartially hydrogenated derivatives thereof, each being optionallysubstituted. In certain embodiments “aryl” means phenyl or naphthyl,each optionally substituted. In many embodiments “aryl” is optionallysubstituted phenyl.

“Arylalkyl” and “Aralkyl”, which may be used interchangeably, mean aradical-R^(a)R^(b) where R^(a) is an alkylene group and R^(b) is an arylgroup as defined herein; e.g., phenylalkyls such as benzyl, phenylethyl,3-(3-chlorophenyl)-2-methylpentyl, and the like are examples ofarylalkyl.

“Arylsulfonyl means a group of the formula —SO₂—R wherein R is aryl asdefined herein.

“Aryloxy” means a group of the formula —O—R wherein R is aryl as definedherein.

“Aralkyloxy” means a group of the formula —O—R—R″ wherein R is alkyleneand R′ is aryl as defined herein.

“Cyanoalkyl”” means a moiety of the formula —R′—R″, where R′ is alkyleneas defined herein and R″ is cyano or nitrile.

“Cycloalkyl” means a monovalent saturated carbocyclic moiety consistingof mono- or bicyclic rings. Cycloalkyl can optionally be substitutedwith one or more substituents, wherein each substituent is independentlyhydroxy, alkyl, alkoxy, halo, haloalkyl, amino, monoalkylamino, ordialkylamino, unless otherwise specifically indicated. Examples ofcycloalkyl moieties include, but are not limited to, cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like,including partially unsaturated derivatives thereof.

“Cycloalkylalkyl” means a moiety of the formula —R′—R″, where R′ isalkylene and R″ is cycloalkyl as defined herein.

“Heteroaryl” means a monocyclic or bicyclic radical of 5 to 12 ringatoms having at least one aromatic ring containing one, two, or threering heteroatoms selected from N, O, or S, the remaining ring atomsbeing C, with the understanding that the attachment point of theheteroaryl radical will be on an aromatic ring. The heteroaryl ring maybe optionally substituted as defined herein. Examples of heteroarylmoieties include, but are not limited to, optionally substitutedimidazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl,thiadiazolyl, pyrazinyl, thienyl, benzothienyl, thiophenyl, furanyl,pyranyl, pyridyl, pyrrolyl, pyrazolyl, pyrimidyl, quinolinyl,isoquinolinyl, benzofuryl, benzothiophenyl, benzothiopyranyl,benzimidazolyl, benzooxazolyl, benzooxadiazolyl, benzothiazolyl,benzothiadiazolyl, benzopyranyl, indolyl, isoindolyl, triazolyl,triazinyl, quinoxalinyl, purinyl, quinazolinyl, quinolizinyl,naphthyridinyl, pteridinyl, carbazolyl, azepinyl, diazepinyl, acridinyland the like, including partially hydrogenated derivatives thereof, eachoptionally substituted.

Heteroarylalkyl” or “heteroaralkyl” means a group of the formula —R—R′wherein R is alkylene and R′ is heteroaryl as defined herein.

“Heteroarylsulfonyl means a group of the formula —SO₂—R wherein R isheteroaryl as defined herein.

“Heteroaryloxy” means a group of the formula —O—R wherein R isheteroaryl as defined herein.

“Heteroaralkyloxy” means a group of the formula —O—R—R″ wherein R isalkylene and R′ is heteroaryl as defined herein.

The terms “halo”, “halogen” and “halide”, which may be usedinterchangeably, refer to a substituent fluoro, chloro, bromo, or iodo.

“Haloalkyl” means alkyl as defined herein in which one or more hydrogenhas been replaced with same or different halogen. Exemplary haloalkylsinclude —CH₂Cl, —CH₂CF₃, —CH₂CCl₃, perfluoroalkyl (e.g., —CF₃), and thelike.

“Haloalkoxy” means a moiety of the formula —OR, wherein R is a haloalkylmoiety as defined herein. An exemplary haloalkoxy is difluoromethoxy.

“Heterocycloamino” means a saturated ring wherein at least one ring atomis N, NH or N-alkyl and the remaining ring atoms form an alkylene group.

“Heterocyclyl” means a monovalent saturated moiety, consisting of one tothree rings, incorporating one, two, or three or four heteroatoms(chosen from nitrogen, oxygen or sulfur). The heterocyclyl ring may beoptionally substituted as defined herein. Examples of heterocyclylmoieties include, but are not limited to, optionally substitutedpiperidinyl, piperazinyl, homopiperazinyl, azepinyl, pyrrolidinyl,pyrazolidinyl, imidazolinyl, imidazolidinyl, pyridinyl, pyridazinyl,pyrimidinyl, oxazolidinyl, isoxazolidinyl, morpholinyl, thiazolidinyl,isothiazolidinyl, quinuclidinyl, quinolinyl, isoquinolinyl,benzimidazolyl, thiadiazolylidinyl, benzothiazolidinyl,benzoazolylidinyl, dihydrofuryl, tetrahydrofuryl, dihydropyranyl,tetrahydropyranyl, thiamorpholinyl, thiamorpholinylsulfoxide,thiamorpholinylsulfone, dihydroquinolinyl, dihydrisoquinolinyl,tetrahydroquinolinyl, tetrahydrisoquinolinyl, and the like.

“Heterocyclylalkyl” means a moiety of the formula —R—R′ wherein R isalkylene and R′ is heterocyclyl as defined herein.

“Heterocyclyloxy” means a moiety of the formula —OR wherein R isheterocyclyl as defined herein.

“Heterocyclylalkoxy” means a moiety of the formula —OR—R′ wherein R isalkylene and R′ is heterocyclyl as defined herein.

“Hydroxyalkoxy” means a moiety of the formula —OR wherein R ishydroxyalkyl as defined herein.

“Hydroxyalkylamino” means a moiety of the formula —NR—R′ wherein R ishydrogen or alkyl and R′ is hydroxyalkyl as defined herein.

“Hydroxyalkylaminoalkyl” means a moiety of the formula —R—NR′—R″ whereinR is alkylene, R′ is hydrogen or alkyl, and R″ is hydroxyalkyl asdefined herein.

“Hydroxycarbonylalkyl” or “carboxyalkyl” means a group of the formula—R—(CO)—OH where R is alkylene as defined herein.

“Hydroxyalkyloxycarbonylalkyl” or “hydroxyalkoxycarbonylalkyl” means agroup of the formula —R—C(O)—O—R—OH wherein each R is alkylene and maybe the same or different.

“Hydroxyalkyl” means an alkyl moiety as defined herein, substituted withone or more, preferably one, two or three hydroxy groups, provided thatthe same carbon atom does not carry more than one hydroxy group.Representative examples include, but are not limited to, hydroxymethyl,2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl,1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl,4-hydroxybutyl, 2,3-dihydroxypropyl, 2-hydroxy-1-hydroxymethylethyl,2,3-dihydroxybutyl, 3,4-dihydroxybutyl and2-(hydroxymethyl)-3-hydroxypropyl

“Hydroxycycloalkyl” means a cycloalkyl moiety as defined herein whereinone, two or three hydrogen atoms in the cycloalkyl radical have beenreplaced with a hydroxy substituent. Representative examples include,but are not limited to, 2-, 3-, or 4-hydroxycyclohexyl, and the like.

“Urea” or “ureido” means a group of the formula —NR′—C(O)—NR″R″″ whereinR′, R″ and R″″ each independently is hydrogen or alkyl.

“Carbamate” means a group of the formula —O—C(O)—NR′R″ wherein R′ and R″each independently is hydrogen or alkyl.

“Carboxy” means a group of the formula —O—C(O)—OH.

“Sulfonamido” means a group of the formula —SO₂—NR′R″ wherein R′, R″ andR″″ each independently is hydrogen or alkyl.

“Optionally substituted”, when used in association with “aryl”, phenyl”,“heteroaryl” “cycloalkyl” or “heterocyclyl”, means an aryl, phenyl,heteroaryl, cycloalkyl or heterocyclyl which is optionally substitutedindependently with one to four substituents, preferably one or twosubstituents selected from alkyl, cycloalkyl, cycloalkylalkyl,heteroalkyl, hydroxyalkyl, halo, nitro, cyano, hydroxy, alkoxy, amino,acylamino, mono-alkylamino, di-alkylamino, halo alkyl, haloalkoxy,heteroalkyl, —COR, —SO₂R (where R is hydrogen, alkyl, phenyl orphenylalkyl), —(CR′R″)_(n)—COOR (where n is an integer from 0 to 5, R′and R″ are independently hydrogen or alkyl, and R is hydrogen, alkyl,cycloalkyl, cycloalkylalkyl, phenyl or phenylalkyl), or—(CR′R″)_(n)—CONR^(a)R^(b) (where n is an integer from 0 to 5, R′ and R″are independently hydrogen or alkyl, and R^(a) and R^(b) are,independently of each other, hydrogen, alkyl, cycloalkyl,cycloalkylalkyl, phenyl or phenylalkyl). In certain embodiments optionalsubstituents for “aryl”, phenyl”, “heteroaryl” “cycloalkyl” or“heterocyclyl” include alkyl, halo, haloalkyl, alkoxy, cyano, amino andalkylsulfonyl. In many embodiments the substituents are methyl, fluoro,chloro, trifluoromethyl, methoxy, amino and methanesulfonyl.

“Leaving group” means the group with the meaning conventionallyassociated with it in synthetic organic chemistry, i.e., an atom orgroup displaceable under substitution reaction conditions. Examples ofleaving groups include, but are not limited to, halogen, alkane- orarylenesulfonyloxy, such as methanesulfonyloxy, ethanesulfonyloxy,thiomethyl, benzenesulfonyloxy, tosyloxy, and thienyloxy,dihalophosphinoyloxy, optionally substituted benzyloxy, isopropyloxy,acyloxy, and the like.

“Modulator” means a molecule that interacts with a target. Theinteractions include, but are not limited to, agonist, antagonist, andthe like, as defined herein.

“Optional” or “optionally” means that the subsequently described eventor circumstance may but need not occur, and that the descriptionincludes instances where the event or circumstance occurs and instancesin which it does not.

“Disease” and “Disease state” means any disease, condition, symptom,disorder or indication.

“Inert organic solvent” or “inert solvent” means the solvent is inertunder the conditions of the reaction being described in conjunctiontherewith, including for example, benzene, toluene, acetonitrile,tetrahydrofuran, N,N-dimethylformamide, chloroform, methylene chlorideor dichloromethane, dichloroethane, diethyl ether, ethyl acetate,acetone, methyl ethyl ketone, methanol, ethanol, propanol, isopropanol,tert-butanol, dioxane, pyridine, and the like. Unless specified to thecontrary, the solvents used in the reactions of the present inventionare inert solvents.

“Pharmaceutically acceptable” means that which is useful in preparing apharmaceutical composition that is generally safe, non-toxic, andneither biologically nor otherwise undesirable and includes that whichis acceptable for veterinary as well as human pharmaceutical use.

“Pharmaceutically acceptable salts” of a compound means salts that arepharmaceutically acceptable, as defined herein, and that possess thedesired pharmacological activity of the parent compound. Such saltsinclude:

acid addition salts formed with inorganic acids such as hydrochloricacid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, andthe like; or formed with organic acids such as acetic acid,benzenesulfonic acid, benzoic, camphorsulfonic acid, citric acid,ethanesulfonic acid, fumaric acid, glucoheptonic acid, gluconic acid,glutamic acid, glycolic acid, hydroxynaphtoic acid,2-hydroxyethanesulfonic acid, lactic acid, maleic acid, malic acid,malonic acid, mandelic acid, methanesulfonic acid, muconic acid,2-naphthalenesulfonic acid, propionic acid, salicylic acid, succinicacid, tartaric acid, p-toluenesulfonic acid, trimethylacetic acid, andthe like; or

salts formed when an acidic proton present in the parent compound eitheris replaced by a metal ion, e.g., an alkali metal ion, an alkaline earthion, or an aluminum ion; or coordinates with an organic or inorganicbase. Acceptable organic bases include diethanolamine, ethanolamine,N-methylglucamine, triethanolamine, tromethamine, and the like.Acceptable inorganic bases include aluminum hydroxide, calciumhydroxide, potassium hydroxide, sodium carbonate and sodium hydroxide.

The preferred pharmaceutically acceptable salts are the salts formedfrom acetic acid, hydrochloric acid, sulphuric acid, methanesulfonicacid, maleic acid, phosphoric acid, tartaric acid, citric acid, sodium,potassium, calcium, zinc, and magnesium.

It should be understood that all references to pharmaceuticallyacceptable salts include solvent addition forms (solvates) or crystalforms (polymorphs) as defined herein, of the same acid addition salt.

“Protective group” or “protecting group” means the group whichselectively blocks one reactive site in a multifunctional compound suchthat a chemical reaction can be carried out selectively at anotherunprotected reactive site in the meaning conventionally associated withit in synthetic chemistry. Certain processes of this invention rely uponthe protective groups to block reactive nitrogen and/or oxygen atomspresent in the reactants. For example, the terms “amino-protectinggroup” and “nitrogen protecting group” are used interchangeably hereinand refer to those organic groups intended to protect the nitrogen atomagainst undesirable reactions during synthetic procedures. Exemplarynitrogen protecting groups include, but are not limited to,trifluoroacetyl, acetamido, benzyl (Bn), benzyloxycarbonyl(carbobenzyloxy, CBZ), p-methoxybenzyloxycarbonyl,p-nitrobenzyloxycarbonyl, tert-butoxycarbonyl (BOC), and the like. Theartisan in the art will know how to chose a group for the ease ofremoval and for the ability to withstand the following reactions.

“Solvates” means solvent additions forms that contain eitherstoichiometric or non stoichiometric amounts of solvent. Some compoundshave a tendency to trap a fixed molar ratio of solvent molecules in thecrystalline solid state, thus forming a solvate. If the solvent is waterthe solvate formed is a hydrate, when the solvent is alcohol, thesolvate formed is an alcoholate. Hydrates are formed by the combinationof one or more molecules of water with one of the substances in whichthe water retains its molecular state as H₂O, such combination beingable to form one or more hydrate.

“Subject” means mammals and non-mammals. Mammals means any member of themammalia class including, but not limited to, humans; non-human primatessuch as chimpanzees and other apes and monkey species; farm animals suchas cattle, horses, sheep, goats, and swine; domestic animals such asrabbits, dogs, and cats; laboratory animals including rodents, such asrats, mice, and guinea pigs; and the like. Examples of non-mammalsinclude, but are not limited to, birds, and the like. The term “subject”does not denote a particular age or sex.

“Disorders of the urinary tract” or “uropathy” used interchangeably with“symptoms of the urinary tract” means the pathologic changes in theurinary tract. Examples of urinary tract disorders include, but are notlimited to, incontinence, benign prostatic hypertrophy (BPH),prostatitis, detrusor hyperreflexia, outlet obstruction, urinaryfrequency, nocturia, urinary urgency, overactive bladder, pelvichypersensitivity, urge incontinence, urethritis, prostatodynia,cystitis, idiophatic bladder hypersensitivity, and the like.

“Disease states associated with the urinary tract” or “urinary tractdisease states” or “uropathy” used interchangeably with “symptoms of theurinary tract” mean the pathologic changes in the urinary tract, ordysfunction of urinary bladder smooth muscle or its innervation causingdisordered urinary storage or voiding. Symptoms of the urinary tractinclude, but are not limited to, overactive bladder (also known asdetrusor hyperactivity), outlet obstruction, outlet insufficiency, andpelvic hypersensitivity.

“Overactive bladder” or “detrusor hyperactivity” includes, but is notlimited to, the changes symptomatically manifested as urgency,frequency, altered bladder capacity, incontinence, micturitionthreshold, unstable bladder contractions, sphincteric spasticity,detrusor hyperreflexia (neurogenic bladder), detrusor instability, andthe like.

“Outlet obstruction” includes, but is not limited to, benign prostatichypertrophy (BPH), urethral stricture disease, tumors, low flow rates,difficulty in initiating urination, urgency, suprapubic pain, and thelike.

“Outlet insufficiency” includes, but is not limited to, urethralhypermobility, intrinsic sphincteric deficiency, mixed incontinence,stress incontinence, and the like.

“Pelvic Hypersensitivity” includes, but is not limited to, pelvic pain,interstitial (cell) cystitis, prostatodynia, prostatitis, vulvadynia,urethritis, orchidalgia, overactive bladder, and the like.

“Respiratory disorder” refers to, without limitation, chronicobstructive pulmonary disease (COPD), asthma, bronchospasm, and thelike.

“Gastrointestinal disorder” (“GI disorder”) refers to, withoutlimitation, Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease(IBD), biliary colic and other biliary disorders, renal colic,diarrhea-dominant IBS, pain associated with GI distension, and the like.

“Pain” includes, without limitation, inflammatory pain; surgical pain;visceral pain; dental pain; premenstrual pain; central pain; pain due toburns; migraine or cluster headaches; nerve injury; neuritis;neuralgias; poisoning; ischemic injury; interstitial cystitis; cancerpain; viral, parasitic or bacterial infection; post-traumatic injury; orpain associated with irritable bowel syndrome.

“Therapeutically effective amount” means an amount of a compound that,when administered to a subject for treating a disease state, issufficient to effect such treatment for the disease state. The“therapeutically effective amount” will vary depending on the compound,disease state being treated, the severity or the disease treated, theage and relative health of the subject, the route and form ofadministration, the judgment of the attending medical or veterinarypractitioner, and other factors.

The terms “those defined above” and “those defined herein” whenreferring to a variable incorporates by reference the broad definitionof the variable as well as preferred, more preferred and most preferreddefinitions, if any.

“Treating” or “treatment” of a disease state includes:

-   -   (i) preventing the disease state, i.e. causing the clinical        symptoms of the disease state not to develop in a subject that        may be exposed to or predisposed to the disease state, but does        not yet experience or display symptoms of the disease state.    -   (ii) inhibiting the disease state, i.e., arresting the        development of the disease state or its clinical symptoms, or    -   (iii) relieving the disease state, i.e., causing temporary or        permanent regression of the disease state or its clinical        symptoms.

The terms “treating”, “contacting” and “reacting” when referring to achemical reaction means adding or mixing two or more reagents underappropriate conditions to produce the indicated and/or the desiredproduct. It should be appreciated that the reaction which produces theindicated and/or the desired product may not necessarily result directlyfrom the combination of two reagents which were initially added, i.e.,there may be one or more intermediates which are produced in the mixturewhich ultimately leads to the formation of the indicated and/or thedesired product.

Nomenclature and Structures

In general, the nomenclature used in this application is based onAUTONOM™ v.4.0, a Beilstein Institute computerized system for thegeneration of IUPAC systematic nomenclature. Chemical structures shownherein were prepared using ISIS® version 2.2. Any open valency appearingon a carbon, oxygen sulfur or nitrogen atom in the structures hereinindicates the presence of a hydrogen atom unless indicated otherwise.Where a nitrogen-containing heteroaryl ring is shown with an openvalency on a nitrogen atom, and variables such as R^(a), R^(b) or R^(c)are shown on the heteroaryl ring, such variables may be bound or joinedto the open valency nitrogen. Where a chiral center exists in astructure but no specific stereochemistry is shown for the chiralcenter, both enantiomers associated with the chiral center areencompassed by the structure. Where a structure shown herein may existin multiple tautomeric forms, all such tautomers are encompassed by thestructure.

All patents and publications identified herein are incorporated hereinby reference in their entirety.

Compounds of the Invention

The invention provides compounds of the formula I:

or pharmaceutically acceptable salts thereof,wherein:

R¹ is: C₁₋₆alkyl; or halo;

R² is: C₃₋₆cycloalkyl; C₁₋₆alkoxy-C₁₋₆alkyl; hydroxy-C₁₋₆alkyl; orheteroaryl-C₁₋₆alkyl;

R³ is: C₁₋₆alkyl; hydroxy-C₁₋₆alkyl; C₁₋₆alkoxy-C₁₋₆alkyl;halo-C₁₋₆alkyl; C₃₋₆cycloalkyl; C₃₋₆cycloalkyl-C₁₋₆alkyl; phenyloptionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl; or phenyl-C₁₋₆alkyl wherein the phenyl portion thereofis optionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl;

R⁴ and R⁵ each independently is: hydrogen; or fluoro;

X is: N; or CR^(a) wherein R^(a) is C₁₋₆alkyl or halo;

Y is: N; or CR^(b) wherein R^(b) is hydrogen or C₁₋₆alkyl; and

Z is: N; or CR^(c); wherein R^(c) is hydrogen or C₁₋₆alkyl.

In certain embodiments of formula I, R⁴ and R⁵ are hydrogen.

In certain embodiments of formula I, one of R⁴ and R⁵ is fluoro and theothers are hydrogen.

In embodiments of the invention, the subject compounds may berepresented by formula II:

wherein X, Y, R′, R², R³ and R⁴ are as defined herein.

In many embodiments of formula I or formula II, R¹ is methyl or halo.

In certain embodiments of formula I or formula II, R¹ is methyl.

In certain embodiments of formula I or formula II, R¹ is chloro.

In certain embodiments of formula I or formula II, R² is C₃₋₆cycloalkyl.

In certain embodiments of formula I or formula II, R² is cyclopropyl.

In certain embodiments of formula I or formula II, R² isC₁₋₆alkoxy-C₁-6alkyl.

In certain embodiments of formula I or formula II, R² is2-methoxy-1-methyl-ethyl.

In certain embodiments of formula I or formula II, R² ishydroxy-C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R² is2-hydroxy-1-methyl-ethyl.

In certain embodiments of formula I or formula II, R² isheteroaryl-C₁₋₆alkyl.

In embodiments of formula I or formula II wherein R² isheteroaryl-C₁₋₆alkyl, the heteroaryl portion thereof may be selectedfrom: pyrimidinyl, pyrazinyl, each optionally substituted once or twicewith C₁₋₆alkyl.

In embodiments of formula I wherein R² is heteroaryl-C₁₋₆alkyl, theheteroaryl portion thereof may be selected from: pyrimidinyl, pyrazinyl,each optionally substituted once with methyl.

In embodiments of formula I or formula II wherein R² isheteroaryl-C₁₋₆alkyl, the C₁₋₆alkyl portion thereof may be selected frommethylene and 1-methyl-ethylene.

In embodiments of formula I or formula II wherein R² isheteroaryl-C₁₋₆alkyl, the C₁₋₆alkyl portion thereof may be selected from—CH₂— and —CH(CH₃)—CH₂—.

In certain embodiments of formula I, R² is heteroaryl-C₁₋₆alkyl selectedfrom: pyrazinyl-methyl; pyridazinyl-methyl; pyrimidinyl-methyl;1-pyrazinyl-ethyl; 1-pyridazinyl-ethyl; and 1-pyrimidinyl-ethyl; whereinthe pyrazinyl, pyridazinyl and pyrimidinyl portions thereof may beoptionally substituted once with methyl.

In certain embodiments of formula I or formula II, R² isheteroaryl-C₁₋₆alkyl selected from: 5-methylpyrazin-2-yl-methyl;1-pyrazin-2-yl-ethyl; pyrimidin-5-yl-methyl;6-methyl-pyridazin-3-yl-methyl; pyridazin-3-yl-methyl;5-methyl-pyrimidin-yl-methyl; and 2-methyl-pyrimidin-5-yl-methyl.

In certain embodiments of formula I or formula II, R² is: cyclopropyl;2-methoxy-1-methyl-ethyl; 2-hydroxy-1-methyl-ethyl;5-methylpyrazin-2-yl-methyl; 1-pyrazin-2-yl-ethyl;pyrimidin-5-yl-methyl; 6-methyl-pyridazin-3-yl-methyl;pyridazin-3-yl-methyl; 5-methyl-pyrimidin-yl-methyl; or2-methyl-pyrimidin-5-yl-methyl.

In certain embodiments of formula I or formula II, R² is:2-hydroxy-1-methyl-ethyl; 5-methylpyrazin-2-yl-methyl;1-pyrazin-2-yl-ethyl; pyrimidin-5-yl-methyl;6-methyl-pyridazin-3-yl-methyl; pyridazin-3-yl-methyl;5-methyl-pyrimidin-yl-methyl; or 2-methyl-pyrimidin-5-yl-methyl.

In certain embodiments of formula I or formula II, R² is:2-hydroxy-1-methyl-ethyl; 5-methylpyrazin-2-yl-methyl; or1-pyrazin-2-yl-ethyl.

In certain embodiments of formula I or formula II, R² is5-methylpyrazin-2-yl-methyl.

In certain embodiments of formula I or formula II, R² is1-pyrazin-2-yl-ethyl.

In certain embodiments of formula I or formula II, R² ispyrimidin-5-yl-methyl.

In certain embodiments of formula I or formula II, R² is6-methyl-pyridazin-3-yl-methyl.

In certain embodiments of formula I or formula II, R² ispyridazin-3-yl-methyl.

In certain embodiments of formula I or formula II, R² is5-methyl-pyrimidin-yl-methyl.

In certain embodiments of formula I or formula II, R² is2-methyl-pyrimidin-5-yl-methyl.

In certain embodiments of formula I or formula II, R³ is: C₁₋₆alkyl;hydroxy-C₁₋₆alkyl; C₁₋₆alkoxy-C₁₋₆alkyl; halo-C₁₋₆alkyl; phenyloptionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl; or phenyl-C₁₋₆alkyl wherein the phenyl portion thereofis optionally substituted with halo, C₁₋₆alkyl, C₁₋₆alkoxy orhalo-C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R³ is: C₁₋₆alkyl;hydroxy-C₁₋₆alkyl; C₁₋₆alkoxy-C₁₋₆alkyl; halo-C₁₋₆alkyl; phenyloptionally substituted with C₁₋₆alkyl; or phenyl-C₁₋₆alkyl wherein thephenyl portion thereof is optionally substituted with C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R³ is: C₁₋₆alkyl;halo-C₁₋₆alkyl; phenyl optionally substituted with C₁₋₆alkyl; orphenyl-C₁₋₆alkyl wherein the phenyl portion thereof is optionallysubstituted with C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R³ is: C₁₋₆alkyl;halo-C₁₋₆alkyl; phenyl optionally substituted with C₁₋₆alkyl; orphenyl-C₁₋₆alkyl wherein the phenyl portion thereof is optionallysubstituted with C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R³ is C₁₋₆alkyl.

In certain embodiments of formula I or formula II, R³ is isopropyl,isobutyl, n-propyl, 3-methyl-butyl, 222-trifluoroethyl, 2-methoxyethyl,phenyl, benzyl, 2-methyl-phenyl; 4-methyl-phenyl; or 2-isopropyl-phenyl.

In certain embodiments of formula I or formula II, R³ is isopropyl,isobutyl, n-propyl, or 3-methyl-butyl.

In certain embodiments of formula I or formula II, R³ is phenyl,2-methyl-phenyl; 4-methyl-phenyl; or 2-isopropyl-phenyl.

In certain embodiments of formula I or formula II, X is —N—.

In certain embodiments of formula I or formula II, X is —CR^(a)—.

In certain embodiments of formula I or formula II, X is —CR^(a)— andR^(a) is hydrogen or halo.

In certain embodiments of formula I or formula II, X is —CR^(a)— andR^(a) is hydrogen.

In certain embodiments of formula I or formula II, Y is N or CR^(b).

In certain embodiments of formula I or formula II, Y is N.

In certain embodiments of formula I or formula II, Y is CR^(b).

In certain embodiments of formula I or formula II, Y is CR^(b) and R^(b)is hydrogen.

In certain embodiments of formula I or formula II, Z is N.

In certain embodiments of formula I or formula II, Z is CR^(c).

In certain embodiments of formula I or formula II, Z is CR^(c) and R^(c)is hydrogen.

In certain embodiments of formula I or formula II, Y and Z are N.

In certain embodiments of formula I or formula II, Y is CR^(b) and Z isCR^(c).

In certain embodiments of formula I or formula II, Y is CR^(b) and Z isCR^(c), and R^(b) and R^(c) are hydrogen.

In certain embodiments of formula I or formula II, Y is N and Z isCR^(c).

In certain embodiments of formula I or formula II, Y is N, Z is CR^(c)and R^(c) is hydrogen.

In certain embodiments of formula I or formula II, Z is N and Y isCR^(b).

In certain embodiments of formula I or formula II, Z is N, Y is CR^(b)and R^(b) is hydrogen.

In certain embodiments the compounds of formulas I and II may berepresented by formula III:

wherein X, R′, R² and R³ are as defined herein for formula I and formulaII.

In certain embodiments the compounds of formulas I and II may berepresented by formula IV:

wherein X, R′, R² and R³ are as defined herein for formula I and formulaII.

In certain embodiments the compounds of formulas I and II may berepresented by formula V:

wherein X, R′, R² and R³ are as defined herein for formula I and formulaII.

Where any of R′, R², R³, R⁴, R⁵, R^(a), R^(b) and R^(c) is alkyl orcontains an alkyl moiety, such alkyl is preferably lower alkyl, i.e.C₁-C₆alkyl, and more preferably C₁-C₄alkyl.

The invention also provides methods for treating a disease or conditionmediated by or otherwise associated with a P2X₃ receptor antagonist, aP2X_(2/3) receptor antagonist, or both, the method comprisingadministering to a subject in need thereof an effective amount of acompound of the invention.

The disease may be genitorurinary disease or urinary tract disease. Inother instances the disease may be a disease is associated with pain.The urinary tract disease may be: reduced bladder capacity; frequentmicturition; urge incontinence; stress incontinence; bladderhyperreactivity; benign prostatic hypertrophy; prostatitis; detrusorhyperreflexia; urinary frequency; nocturia; urinary urgency; overactivebladder; pelvic hypersensitivity; urethritis; prostatitits; pelvic painsyndrome; prostatodynia; cystitis; or idiophatic bladderhypersensitivity.

The disease associated with pain may be: inflammatory pain; surgicalpain; visceral pain; dental pain; premenstrual pain; central pain; paindue to burns; migraine or cluster headaches; nerve injury; neuritis;neuralgias; poisoning; ischemic injury; interstitial cystitis; cancerpain; viral, parasitic or bacterial infection; post-traumatic injury; orpain associated with irritable bowel syndrome.

The disease may be a respiratory disorder, such as chronic obstructivepulmonary disorder (COPD), asthma, or bronchospasm, or agastrointestinal (GI) disorder such as Irritable Bowel Syndrome (IBS),Inflammatory Bowel Disease (IBD), biliary colic and other biliarydisorders, renal colic, diarrhea-dominant IBS, pain associated with GIdistension.

Representative compounds in accordance with the methods of the inventionare shown in Table 1, with pKi values for the P2X₃ and P2X_(2/3)receptors.

TABLE 1 # Structure Name P2X3 P2X2/3 1

1-Isobutyl-4-(5-methyl-pyridin- 2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.3 5.78 2

1-Butyl-4-(5-methyl-pyridin-2- yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.38 6.34 3

1-Butyl-4-(5-methyl-pyridin-2- yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl- ethyl)-amide 6.31 4

1-Isopropyl-4-(5-methyl- pyridin-2-yl)-1H-indazole-6- carboxylic acid(5-methyl- pyrazin-2-ylmethyl)-amide 6.58 4.92 5

1-Isopropyl-4-(5-methyl- pyridin-2-yl)-1H-indazole-6- carboxylic acid((S)-2-hydroxy- 1-methyl-ethyl)-amide 5 6

1-(2-Methoxy-ethyl)-4-(5- methyl-pyridin-2-yl)-1H- indazole-6-carboxylicacid (5- methyl-pyrazin-2-ylmethyl)- amide 5.51 5 7

1-(3-Methyl-butyl)-4-(5-methyl- pyridin-2-yl)-1H-indazole-6- carboxylicacid (5-methyl- pyrazin-2-ylmethyl)-amide 7. 47 6.17 8

1-(3-Methyl-butyl)-4-(5-methyl- pyridin-2-yl)-1H-indazole-6 carboxylicacid (6-methyl- pyridazin-3-ylmethyl)-amide 7.66 6.23 9

1-Benzyl-4-(5-methyl-pyridin-2- yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.25 6.25 10

1-Benzyl-4-(5-methyl-pyridin-2- yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl- ethyl)-amide 6.2 5.61 11

1-Benzyl-4-(5-methyl-pyridin-2- yl)-1H-indazole-6-carboxylic acid(6-methyl-pyridazin-3- ylmethyl)-amide 7.62 6.56 12

4-(5-Methyl-pyridin-2-yl)-1- (2,2,2-trifluoro-ethyl)-1H-indazole-6-carboxylic acid (5- methyl-pyrazin-2-ylmethyl)- amide 6.525.7 13

4-(5-Methyl-pyridin-2-yl)-1- (2,2,2-trifluoro-ethyl)-1H-indazole-6-carboxylic acid (6- methyl-pyrazin-3-ylmethyl)- amide 7.196.51 14

4-(5-Methyl-pyridin-2-yl)-1- phenyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.44 6.54 15

4-(5-Methyl-pyridin-2-yl)-1- phenyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl- ethyl)-amide 6.19 5.34 16

4-(5-Methyl-pyridin-2-yl)-1-p- tolyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.7 6.4 17

4-(5-Methyl-pyridin-2-yl)-1-p- tolyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl ethyl)-amide 7.38 4.97 18

4-(5-Methyl-pyridin-2-yl)-1-o- tolyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 8.01 7.26 19

4-(5-Methyl-pyridin-2-yl)-1-o- tolyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl ethyl)-amide 7.98 6 20

1-(2-Isopropyl-phenyl)-4-(5- methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid ((S)- 2-hydroxy-1-methyl-ethyl)- amide 7.556.19 21

1-Isobutyl-4-(5-methyl-pyridin- 2-yl)-1H-indole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.17 5.92 22

1-Isobutyl-4-(5-methyl-pyridin- 2-yl)-1H-indole-6-carboxylic acid((S)-2-hydroxy-1-methyl- ethyl)-amide 6.54 5.14 23

4-(5-Methyl-pyridin-2-yl)-1- phenyl-1H-indole-6-carboxylic acid(5-methyl-pyrazin-2- ylmethyl)-amide 7.73 6.34 24

4-(5-Methyl-pyridin-2-yl)-1- phenyl-1H-indole-6-carboxylic acid((S)-2-hydroxy-1-methyl- ethyl)-amide 6.99 5.54 25

1-Isopropyl-4-(5-methyl- pyridin-2-yl)-1H-indole-6- carboxylic acid(6-methyl- pyridazin-3-ylmethyl)-amide 7.27 5.32 26

1-Isopropyl-4-(5-methyl- pyridin-2-yl)-1H-indole-6- carboxylic acid(5-methyl- pyrazin-2-ylmethyl)-amide 6.26 27

1-Isopropyl-4-(5-methyl- pyridin-2-yl)-1H-indole-6- carboxylic acid((S)-2-hydroxy- 1-methyl-ethyl)-amide 5.48 28

3-Isobutyl-7-(5-methyl-pyridin- 2-yl)-3H-benzoimidazole-5- carboxylicacid (5-methyl- pyrazin-2-ylmethyl)-amide 6.46 29

3-Isobutyl-7-(5-methyl-pyridin- 2-yl)-3H-benzoimidazole-5- carboxylicacid ((S)-2-hydroxy- 1-methyl-ethyl)-amide 5.24

Synthesis

Compounds of the present invention can be made by a variety of methodsdepicted in the illustrative synthetic reaction schemes shown anddescribed below.

The starting materials and reagents used in preparing these compoundsgenerally are either available from commercial suppliers, such asAldrich Chemical Co., or are prepared by methods known to those skilledin the art following procedures set forth in references such as Fieserand Fieser's Reagents for Organic Synthesis; Wiley & Sons: New York,1991, Volumes 1-15; Rodd's Chemistry of Carbon Compounds, ElsevierScience Publishers, 1989, Volumes 1-5 and Supplementals; and OrganicReactions, Wiley & Sons: New York, 1991, Volumes 1-40. The followingsynthetic reaction schemes are merely illustrative of some methods bywhich the compounds of the present invention can be synthesized, andvarious modifications to these synthetic reaction schemes can be madeand will be suggested to one skilled in the art having referred to thedisclosure contained in this application.

The starting materials and the intermediates of the synthetic reactionschemes can be isolated and purified if desired using conventionaltechniques, including but not limited to, filtration, distillation,crystallization, chromatography, and the like. Such materials can becharacterized using conventional means, including physical constants andspectral data.

Unless specified to the contrary, the reactions described hereinpreferably are conducted under an inert atmosphere at atmosphericpressure at a reaction temperature range of from about −78° C. to about150° C., more preferably from about 0° C. to about 125° C., and mostpreferably and conveniently at about room (or ambient) temperature,e.g., about 20° C.

Scheme A below illustrates one synthetic procedure usable to preparespecific compounds of formula I, wherein R is lower alkyl and X, R′, R²and R³ are as defined herein.

In step 1 of Scheme A, nitrobenzoic acid a is subject to iodinationunder sulfuric acid conditions to afford iodo-nitrobenzoic acid b.Benzoic acid compound b then undergoes esterification in step 2 byreaction with alcohol ROH under acidic or basic conditions, oralternatively by an O-alkylation reaction with a suitable alkylatingagent, to yield nitrobenzoic acid ester compound c. The nitro group ofcompound c is reduced in step 3 to provide the corresponding anilineester compound d. In step 4, aniline ester compound d undergoes acyclization reaction with isoamyl nitrate to afford indazole estercompound e. An N-alkylation occurs in step 5 wherein compound e istreated with alkylating agent f to afford N-alkyl indazole estercompound g. In step 6 compound g is reacted with aryl zinc bromidecompound h to give aryl indazole ester compound i. Hydrolysis is carriedout in step 7 under acidic or basic conditions to convert compound i tothe corresponding carboxylic acid compound i. In step 8 an amideformation occurs wherein carboxylic acid compound i is reacted withamine compound k to give aryl indazole amide compound III, which is acompound of formula I in accordance with the invention.

Many variations of Scheme A are possible and will suggest themselves tothose skilled in the art. For example, in some embodiments indazoleester compound e may be reacted with aryl zinc bromide compound h priorto the alkylation reaction of step 5.

Scheme B provides another synthetic route to the compounds of theinvention, wherein R is lower alkyl and X, R′, R² and R³ are as definedherein.

In step 1 of scheme A, aryl nitroaniline carboxylic acid compound mundergoes esterification, in the manner described above in step 2 ofScheme A, to afford nitro aniline ester compound n. Compound n undergoesan iodination reaction in step 2 to form iodo compound o. The nitrogroup of compound o is reduced in step 3 to afford diamino compound o.In step 3 compound p is treated with triethyl orthoformate to effect acyclization and provide benzimidazole ester compound g. Steps 5, 6, 7and 8 of Scheme B may then proceed in the same manner as illustratedabove in Scheme A, to afford compound IV, which is a compound of formulaI in accordance with the invention.

As with Scheme A, many variations are possible in the procedure Scheme Band will be readily apparent to those skilled in the art. Specificdetails for producing compounds of the invention are described in theExamples section below.

Utility

The compounds of the invention are usable for the treatment of a widerange of genitorurinary diseases, conditions and disorders, includingurinary tract disease states associated with bladder outlet obstructionand urinary incontinence conditions such as reduced bladder capacity,frequency of micturition, urge incontinence, stress incontinence,bladder hyperreactivity, benign prostatic hypertrophy (BPH),prostatitis, detrusor hyperreflexia, urinary frequency, nocturia,urinary urgency, overactive bladder, pelvic hypersensitivity,urethritis, prostatitits, pelvic pain syndrome, prostatodynia, cystitis,and idiophatic bladder hypersensitivity, and other symptoms related tooveractive bladder.

The compounds of the invention are expected to find utility asanalgesics in the treatment of diseases and conditions associated withpain from a wide variety of causes, including, but not limited to,inflammatory pain such as pain associated with arthritis (includingrheumatoid arthritis and osteoarthritis), surgical pain, visceral pain,dental pain, premenstrual pain, central pain, pain due to burns,migraine or cluster headaches, nerve injury, neuritis, neuralgias,poisoning, ischemic injury, interstitial cystitis, cancer pain, viral,parasitic or bacterial infection, post-traumatic injuries (includingfractures and sports injuries), and pain associated with functionalbowel disorders such as irritable bowel syndrome.

Further, compounds of the invention are useful for treating respiratorydisorders, including chronic obstructive pulmonary disorder (COPD),asthma, bronchospasm, and the like.

Additionally, compounds of the invention are useful for treatinggastrointestinal disorders, including Irritable Bowel Syndrome (IBS),Inflammatory Bowel Disease (IBD), biliary colic and other biliarydisorders, renal colic, diarrhea-dominant IBS, pain associated with GIdistension, and the like.

Administration and Pharmaceutical Composition

The invention includes pharmaceutical compositions comprising at leastone compound of the present invention, or an individual isomer, racemicor non-racemic mixture of isomers or a pharmaceutically acceptable saltor solvate thereof, together with at least one pharmaceuticallyacceptable carrier, and optionally other therapeutic and/or prophylacticingredients.

In general, the compounds of the invention will be administered in atherapeutically effective amount by any of the accepted modes ofadministration for agents that serve similar utilities. Suitable dosageranges are typically 1-500 mg daily, preferably 1-100 mg daily, and mostpreferably 1-30 mg daily, depending upon numerous factors such as theseverity of the disease to be treated, the age and relative health ofthe subject, the potency of the compound used, the route and form ofadministration, the indication towards which the administration isdirected, and the preferences and experience of the medical practitionerinvolved. One of ordinary skill in the art of treating such diseaseswill be able, without undue experimentation and in reliance uponpersonal knowledge and the disclosure of this application, to ascertaina therapeutically effective amount of the compounds of the presentinvention for a given disease.

Compounds of the invention may be administered as pharmaceuticalformulations including those suitable for oral (including buccal andsub-lingual), rectal, nasal, topical, pulmonary, vaginal, or parenteral(including intramuscular, intraarterial, intrathecal, subcutaneous andintravenous) administration or in a form suitable for administration byinhalation or insufflation. The preferred manner of administration isgenerally oral using a convenient daily dosage regimen which can beadjusted according to the degree of affliction.

A compound or compounds of the invention, together with one or moreconventional adjuvants, carriers, or diluents, may be placed into theform of pharmaceutical compositions and unit dosages. The pharmaceuticalcompositions and unit dosage forms may be comprised of conventionalingredients in conventional proportions, with or without additionalactive compounds or principles, and the unit dosage forms may containany suitable effective amount of the active ingredient commensurate withthe intended daily dosage range to be employed. The pharmaceuticalcompositions may be employed as solids, such as tablets or filledcapsules, semisolids, powders, sustained release formulations, orliquids such as solutions, suspensions, emulsions, elixirs, or filledcapsules for oral use; or in the form of suppositories for rectal orvaginal administration; or in the form of sterile injectable solutionsfor parenteral use. Formulations containing about one (1) milligram ofactive ingredient or, more broadly, about 0.01 to about one hundred(100) milligrams, per tablet, are accordingly suitable representativeunit dosage forms.

The compounds of the invention may be formulated in a wide variety oforal administration dosage forms. The pharmaceutical compositions anddosage forms may comprise a compound or compounds of the presentinvention or pharmaceutically acceptable salts thereof as the activecomponent. The pharmaceutically acceptable carriers may be either solidor liquid. Solid form preparations include powders, tablets, pills,capsules, cachets, suppositories, and dispersible granules. A solidcarrier may be one or more substances which may also act as diluents,flavouring agents, solubilizers, lubricants, suspending agents, binders,preservatives, tablet disintegrating agents, or an encapsulatingmaterial. In powders, the carrier generally is a finely divided solidwhich is a mixture with the finely divided active component. In tablets,the active component generally is mixed with the carrier having thenecessary binding capacity in suitable proportions and compacted in theshape and size desired. The powders and tablets preferably contain fromabout one (1) to about seventy (70) percent of the active compound.Suitable carriers include but are not limited to magnesium carbonate,magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch,gelatine, tragacanth, methylcellulose, sodium carboxymethylcellulose, alow melting wax, cocoa butter, and the like. The term “preparation” isintended to include the formulation of the active compound withencapsulating material as carrier, providing a capsule in which theactive component, with or without carriers, is surrounded by a carrier,which is in association with it. Similarly, cachets and lozenges areincluded. Tablets, powders, capsules, pills, cachets, and lozenges maybe as solid forms suitable for oral administration.

Other forms suitable for oral administration include liquid formpreparations including emulsions, syrups, elixirs, aqueous solutions,aqueous suspensions, or solid form preparations which are intended to beconverted shortly before use to liquid form preparations. Emulsions maybe prepared in solutions, for example, in aqueous propylene glycolsolutions or may contain emulsifying agents, for example, such aslecithin, sorbitan monooleate, or acacia. Aqueous solutions can beprepared by dissolving the active component in water and adding suitablecolorants, flavors, stabilizers, and thickening agents. Aqueoussuspensions can be prepared by dispersing the finely divided activecomponent in water with viscous material, such as natural or syntheticgums, resins, methylcellulose, sodium carboxymethylcellulose, and otherwell known suspending agents. Solid form preparations include solutions,suspensions, and emulsions, and may contain, in addition to the activecomponent, colorants, flavors, stabilizers, buffers, artificial andnatural sweeteners, dispersants, thickeners, solubilizing agents, andthe like.

The compounds of the invention may be formulated for parenteraladministration (e.g., by injection, for example bolus injection orcontinuous infusion) and may be presented in unit dose form in ampoules,pre-filled syringes, small volume infusion or in multi-dose containerswith an added preservative. The compositions may take such forms assuspensions, solutions, or emulsions in oily or aqueous vehicles, forexample solutions in aqueous polyethylene glycol. Examples of oily ornonaqueous carriers, diluents, solvents or vehicles include propyleneglycol, polyethylene glycol, vegetable oils (e.g., olive oil), andinjectable organic esters (e.g., ethyl oleate), and may containformulatory agents such as preserving, wetting, emulsifying orsuspending, stabilizing and/or dispersing agents. Alternatively, theactive ingredient may be in powder form, obtained by aseptic isolationof sterile solid or by lyophilization from solution for constitutionbefore use with a suitable vehicle, e.g., sterile, pyrogen-free water.

The compounds of the invention may be formulated for topicaladministration to the epidermis as ointments, creams or lotions, or as atransdermal patch. Ointments and creams may, for example, be formulatedwith an aqueous or oily base with the addition of suitable thickeningand/or gelling agents. Lotions may be formulated with an aqueous or oilybase and will in general also containing one or more emulsifying agents,stabilizing agents, dispersing agents, suspending agents, thickeningagents, or coloring agents. Formulations suitable for topicaladministration in the mouth include lozenges comprising active agents ina flavored base, usually sucrose and acacia or tragacanth; pastillescomprising the active ingredient in an inert base such as gelatine andglycerine or sucrose and acacia; and mouthwashes comprising the activeingredient in a suitable liquid carrier.

The compounds of the invention may be formulated for administration assuppositories. A low melting wax, such as a mixture of fatty acidglycerides or cocoa butter is first melted and the active component isdispersed homogeneously, for example, by stirring. The moltenhomogeneous mixture is then poured into convenient sized molds, allowedto cool, and to solidify.

The compounds of the invention may be formulated for vaginaladministration. Pessaries, tampons, creams, gels, pastes, foams orsprays containing in addition to the active ingredient such carriers asare known in the art to be appropriate.

The subject compounds may be formulated for nasal administration. Thesolutions or suspensions are applied directly to the nasal cavity byconventional means, for example, with a dropper, pipette or spray. Theformulations may be provided in a single or multidose form. In thelatter case of a dropper or pipette, this may be achieved by the patientadministering an appropriate, predetermined volume of the solution orsuspension. In the case of a spray, this may be achieved for example bymeans of a metering atomizing spray pump.

The compounds of the invention may be formulated for aerosoladministration, particularly to the respiratory tract and includingintranasal administration. The compound will generally have a smallparticle size for example of the order of five (5) microns or less. Sucha particle size may be obtained by means known in the art, for exampleby micronization. The active ingredient is provided in a pressurizedpack with a suitable propellant such as a chlorofluorocarbon (CFC), forexample, dichlorodifluoromethane, trichlorofluoromethane, ordichlorotetrafluoroethane, or carbon dioxide or other suitable gas. Theaerosol may conveniently also contain a surfactant such as lecithin. Thedose of drug may be controlled by a metered valve. Alternatively theactive ingredients may be provided in a form of a dry powder, forexample a powder mix of the compound in a suitable powder base such aslactose, starch, starch derivatives such as hydroxypropylmethylcellulose and polyvinylpyrrolidine (PVP). The powder carrier will form agel in the nasal cavity. The powder composition may be presented in unitdose form for example in capsules or cartridges of e.g., gelatine orblister packs from which the powder may be administered by means of aninhaler.

When desired, formulations can be prepared with enteric coatings adaptedfor sustained or controlled release administration of the activeingredient. For example, the compounds of the present invention can beformulated in transdermal or subcutaneous drug delivery devices. Thesedelivery systems are advantageous when sustained release of the compoundis necessary and when patient compliance with a treatment regimen iscrucial. Compounds in transdermal delivery systems are frequentlyattached to an skin-adhesive solid support. The compound of interest canalso be combined with a penetration enhancer, e.g., Azone(1-dodecylazacycloheptan-2-one). Sustained release delivery systems areinserted subcutaneously into the subdermal layer by surgery orinjection. The subdermal implants encapsulate the compound in a lipidsoluble membrane, e.g., silicone rubber, or a biodegradable polymer,e.g., polylactic acid.

The pharmaceutical preparations are preferably in unit dosage forms. Insuch form, the preparation is subdivided into unit doses containingappropriate quantities of the active component. The unit dosage form canbe a packaged preparation, the package containing discrete quantities ofpreparation, such as packeted tablets, capsules, and powders in vials orampoules. Also, the unit dosage form can be a capsule, tablet, cachet,or lozenge itself, or it can be the appropriate number of any of thesein packaged form.

Other suitable pharmaceutical carriers and their formulations aredescribed in Remington: The Science and Practice of Pharmacy 1995,edited by E. W. Martin, Mack Publishing Company, 19th edition, Easton,Pa. Representative pharmaceutical formulations containing a compound ofthe present invention are described below.

EXAMPLES

The following preparations and examples are given to enable thoseskilled in the art to more clearly understand and to practice thepresent invention. They should not be considered as limiting the scopeof the invention, but merely as being illustrative and representativethereof.

Unless otherwise stated, all temperatures including melting points(i.e., MP) are in degrees celsius (° C.). It should be appreciated thatthe reaction which produces the indicated and/or the desired product maynot necessarily result directly from the combination of two reagentswhich were initially added, i.e., there may be one or more intermediateswhich are produced in the mixture which ultimately leads to theformation of the indicated and/or the desired product. The followingabbreviations may be used in the Preparations and Examples.

ABBREVIATIONS

CDI 1,1′-carbonyl diimidazole

DBU 1,8-diazabicyclo[5.4.0]undec-7-ene

DCM dichloromethane/methylene chloride

DIPEA diisopropyl ethylamine

DME 1,2-dimethoxyethane (glyme)

DMF N,N-dimethylformamide

DMFDMA N,N-dimethylformamide dimethyl acetal

DMSO dimethyl sulfoxide

DMAP 4-dimethylaminopyridine

ECDI 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimide

EtOAc ethyl acetate

EtOH ethanol

Et₃N triethylamine

gc gas chromatography

HMPA hexamethylphosphoramide

HOAt 1-Hydroxy-7-Azabenzotriazole

HOBt N-Hydroxybenzotriazole

hplc high performance liquid chromatography

IPA isopropanol

mCPBA m-chloroperbenzoic acid

MeCN acetonitrile

NMM N-methyl morpholine

NMP N-methylpyrrolidinone

TEA triethylamine

THF tetrahydrofuran

LDA lithium diisopropylamine

TLC thin layer chromatography

Preparation 1 (S)-2-Methoxy-1-methyl-ethylamine

The synthetic procedure used in this preparation is outlined below inScheme B.

Step 1 (S)-Boc-2-amino-propanol

D-Alanine (3.5 g, 39.3 mmol) was added in small portions to a suspensionof LiAlH₄ (2.89 g, 76.26 mmol) in refluxing THF. Refluxing continued for12 hours, then the reaction mixture was cooled to 0° C., and excessreagent was quenched by careful addition of an aqueous 15% NaOH solution(3 ml) and water (9 ml). After stirring at room temperature for 10minutes, a solution of (Boc)₂O (8.31 g, 38.13 mmol) in CH₂Cl₂ (40 ml)was added. The reaction mixture was stirred at 60° C. for 6 hours,cooled to room temperature, filtered through a pad of anhydrous Na₂SO₄,and the filtrate concentrated under vacuum. Purification of the residueby silica-gel column chromatography afforded (S)-Boc-2-amino-propanol asa white solid, yield: 63%. MS (M+H)=176.

Step 2 (S)-Boc-2-methoxy-1-methyl-ethylamine

To a solution of (S)-Boc-2-amino-propanol (2.00 g, 11.4 mmol) wassuccessively added Ag₂O (5.89 g, 25.4 mmol) and Methyl iodide (16.00 g,112.7 mmol) at room temperature. The reaction mixture was stirred atroom temperature for 2 days. Solid was filtered off and the filtrate wasconcentrated under vacuum to afford(S)-Boc-2-methoxy-1-methyl-ethylamine as a colorless oil that was usedwithout further purification.

Step 3 (S)-2-methoxy-1-methyl-ethylamine

(S)-Boc-2-methoxy-1-methyl-ethylamine was dissolved in MeOH (40 mL) and3 M HCl (10 mL) was added. The reaction mixture was stirred overnight atroom temperature, then solvent was removed under reduced pressure andthe residue was co-evaporated with additional EtOH (20 mL) to afford(S)-2-methoxy-1-methyl-ethylamine as light-brown oil in hydrochlorideform (1.42 g, 100%). MS (M+H)=90.

Similarly prepared was (S)-2-ethoxy-1-methyl-ethylamine.

Similarly prepared from L-alanine were ®-2-methoxy-1-methyl-ethylamineand ®-2-ethoxy-1-methyl-ethylamine.

Preparation 2 1-Pyrazin-2-yl-ethylamine

The synthetic procedure used in this preparation is outlined below inScheme C.

To a solution of 1-pyrazin-2-yl-ethanone (2.0 g, 15.85 mmol) andammonium acetate (19.337 g, 158.5 mmol) in methanol (50 mL) was addedsodium cyanoborohydride (0.7 g, 11.1 mmol) in one portion. The reactionmixture was stirred overnight at room temperature. After removal ofmethanol, water (20 mL) was added to the residue and the resultingsolution was basified by addition of sodium hydroxide to pH=13. Theaqueous solution was extracted with dichloromethane and the combinedorganic phase was dried over sodium sulfate. Removal of the solventunder reduced pressure afforded 14.62 g of 1-pyrazin-2-yl-ethylamine,yield: 75%. MS (M+H)=124.

Similarly prepared from the appropriate heteroaryl methyl ketones orphenyl methyl ketones were: 1-pyridin-2-yl-ethylamine,1-pyridin-3-yl-ethylamine, 1-pyridin-4-yl-ethylamine,1-(2-fluoro-phenyl)-ethylamine, 1-(3-Fluoro-phenyl)-ethylamine,1-(4-methanesulfonyl-phenyl)-ethylamine, 1-thien-3-yl-ethylamine,1-furan-2-yl-ethylamine, 1-(5-methyl-furan)-2-yl-ethylamine,1-thiazol-2-yl-ethylamine, 1-thien-2-yl-ethylamine,1-pyrimidin-2-yl-ethylamine, C-(6-methyl-pyridazin-3-yl)-methylamine,C-(5-methyl-pyrazin-2-yl)-methylamine, and 1-pyridazin-4-yl-ethylamine.

Preparation 3 4-Iodo-1H-indazole-6-carboxylic acid methyl ester

The synthetic procedure used in this preparation is outlined below inScheme D.

Step 1 3-Iodo-4-methyl-5-nitro-benzoic acid

To a mixture of iodine (19.6 g, 77.3 mmol) in fuming sulfuric acid (35mL) was added 4-methyl-3-nitro-benzoic acid (10.0 g, 55.2 mmol). Themixture was stirred at 85° C. over night, then cooled to roomtemperature and poured over ice. The mixture was partitioned betweenethyl acetate and aqueous sodium bisulfite, and the organic layer wasseparated, dried over MgSO₄, filtered and concentrated under reducedpressure to give 16.06 g (95%) of 3-iodo-4-methyl-5-nitro-benzoic acid.

Step 2 3-Iodo-4-methyl-5-nitro-benzoic acid methyl ester

To a solution of 3-iodo-4-methyl-5-nitro-benzoic acid (16.06 g, 52.3mmol) in acetone (300 mL) was added K₂CO₃ (14.46 g, 104.6 mmol) followedby methyl iodide ((3.91 mL, 62.76 mmol). The reaction mixture wasstirred at 40° C. overnight, then cooled to room temperature andpartitioned between ethyl acetate and brine. The organic layer wasseparated, dried over MgSO₄, filtered and concentrated under reducedpressure to provide 16.5 g (98%) of 3-iodo-4-methyl-5-nitro-benzoic acidmethyl ester.

Step 3 3-Amino-5-iodo-4-methyl-benzoic acid methyl ester

To a solution of 3-iodo-4-methyl-5-nitro-benzoic acid methyl ester (2.0g, 6.23 mmol) in a mixture of THF (40 mL) and methanol (1 mL) was addedSnCl₂ dihydrate (4.22 g, 18.69 mmol). The reaction mixture was stirredat 60° C. for six hours, then cooled to room temperature and partitionedbetween ethyl acetate and saturated aqueous sodium bicarbonate. Theorganic layer was separated, dried over MgSO₄, filtered and concentratedunder reduced pressure. The residue was purified by columnchromatography to afford 1.22 g (67%) of 3-amino-5-iodo-4-methyl-benzoicacid methyl ester.

Step 4 4-Iodo-1H-indazole-6-carboxylic acid methyl ester

To a solution of 3-amino-5-iodo-4-methyl-benzoic acid methyl ester (1.22g, 4.21 mmol) in acetic acid (20 mL) was added isoamyl nitrate (0.675mL, 4.63 mmol). The mixture was stirred at room temperature for 30minutes and then concentrated under reduced pressure. The residue waspartitioned between dichloromethane and saturated aqueous sodiumbicarbonate. The organic layer was separated, dried over MgSO₄, filteredand concentrated under reduced pressure. The residue was purified bycolumn chromatography to give 1.15 g (91%) of4-iodo-1H-indazole-6-carboxylic acid methyl ester, MS (M+H)=303.

Preparation 4 7-Iodo-3H-benzoimidazole-5-carboxylic acid methyl ester

The synthetic procedure used in this preparation is outlined below inScheme E.

Step 1 4-Amino-3-nitro-benzoic acid methyl ester

To a mixture of 4-amino-3-nitro-benzoic acid (10.0 g, 54.9 mm0l)suspended in methanol (150 mL) was added thionyl chloride (3.99 mL, 54.9mmol). The mixture was heated to reflux overnight, then cooled to roomtemperature and filtered. The solid recovered by filtration was rinsedwith cold methanol and dried to give 8.68 g (81%) of4-amino-3-nitro-benzoic acid methyl ester.

Step 2 4-Amino-3-iodo-5-nitro-benzoic acid methyl ester

To a solution of 4-amino-3-nitro-benzoic acid methyl ester (4.6 g, 23.45mmol) in ethanol (120 mL) was added iodine (8.33 g, 32.83 mmol),followed by Ag₂SO₄ (10.24 g 32.83 mmol). The mixture was stirredovernight at room temperature and then filtered. The filtrate wasconcentrated under reduced pressure and the residue was purified bycolumn chromatography to give 4.98 g (66%) of4-amino-3-iodo-5-nitro-benzoic acid methyl ester.

Step 3 3,4-Diamino-5-iodo-benzoic acid methyl ester

To a solution of 4-amino-3-iodo-5-nitro-benzoic acid methyl ester inethyl acetate (50 mL) was added SnCl₂ dihydrate. The mixture was heatedto 70° C. for two hours, then cooled to room temperature and partitionedbetween ethyl acetate and saturated aqueous sodium bicarbonate. Theorganic layer was separated, dried over MgSO₄, filtered and concentratedunder reduced pressure to provide 1.68 g (quantitative) of3,4-diamino-5-iodo-benzoic acid methyl ester.

Step 4 7-Iodo-3H-benzoimidazole-5-carboxylic acid methyl ester

To a solution of 3,4-diamino-5-iodo-benzoic acid methyl ester (1.68 g,5.75 mmol) in THF (20 mL) was added trimethyl orthoformate (1.26 mL,11.5 mmol) and 4-toluenesulfonic acid (11 mg, 0.057 mmol). The mixturewas stirred at room temperature overnight, then partitioned betweenethyl acetate and water. The organic layer was separated, dried overMgSO₄, filtered and concentrated under reduced pressure to give 783 mg(45%) of 7-Iodo-3H-benzoimidazole-5-carboxylic acid methyl ester, MS(M+H)=303.

Example 1 1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide

The synthetic procedure used in this preparation is outlined below inScheme F.

Step 1 4-Iodo-1-isopropyl-1H-indazole-6-carboxylic acid methyl ester

To a solution of 4-iodo-1H-indazole-6-carboxylic acid methyl ester (2.0g, 6.62 mmol) in DMF (50 mL) was added Cs₂CO₃ (4.32 g, 13.24 mmol)followed by 2-iodopropane (0.5 mL, 7.94 mmol). The reaction mixture wasstirred overnight at room temperature, then partitioned between waterand ethyl acetate. The organic layer was separated, dried over MgSO₄,filtered and concentrated under reduced pressure. The residue waspurified by column chromatography to provide 1.13 g (50%) of4-iodo-1-isopropyl-1H-indazole-6-carboxylic acid methyl ester (0.73 g(32%) of the regioisomer 4-iodo-2-isopropyl-2H-indazole-6-carboxylicacid methyl ester was also recovered).

Step 2 1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid methyl ester

To a solution of 4-iodo-1-isopropyl-1H-indazole-6-carboxylic acid methylester (1.13 g, 3.28 mmol) in THF (30 mL) was added Pd(PPh₃)₄ (0.2 g,0.164 mmol), followed by 5-methyl-pyridinyl zinc bromide ((19.7 mL of0.5M solution in THF, 9.86 mmol). The reaction mixture was stirredovernight at room temperature, then quenched by addition of saturatedaqueous NH₄Cl solution. The mixture was partitioned between water andethyl acetate, and the organic layer was separated, dried over MgSO₄,filtered and concentrated under reduced pressure. Purification by columnchromatography gave 0.5 g (50%) of1-isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acidmethyl ester.

Step 3 1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid

1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acidmethyl ester (0.5 g, 1.62 mmol) was dissolved in methanol (30 mL) and 2Naqueous NaOH (3 mL) was added. The reaction mixture was stirred at roomtemperature overnight, then partitioned between 1N aqueous HCl and ethylacetate. The organic layer was separated, dried over MgSO₄, filtered andconcentrated under reduced pressure to provide 0.48 g (100%) of1-isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid

Step 4 1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide

To a solution of1-isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(0.24 g, 0.814 mmol) in acetonitril was addedC-(5-methyl-pyrazin-2-yl)-methylamine (0.12 g, 0.976 mmol), EDCI (0.23g, 1.22 mmol), HOBt (0.16 g, 1.22 mmol), and NMM (0.45 mL, 4.07 mmol).The reaction mixture was stirred at room temperature overnight, thenpartitioned between water and ethyl acetate. The organic layer wasseparated, dried over MgSO₄, filtered and concentrated under reducedpressure. Purification of the residue by column chromatography gave0.144 g (44%) of1-isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide MS (M+H)=401.

Similarly prepared, replacing C-(5-methyl-pyrazin-2-yl)-methylamine with(S)-2-amino-propan-1-ol, was1-isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide, MS (M+H)=353.

Similarly prepared, replacing 2-iodopropane with1-iodo-2-methyl-propane, was1-Isobutyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide, MS (M+H)=415.

Additional compounds prepared by the above procedure are shown in Table1.

Example 2 4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide

The synthetic procedure used in this preparation is outlined below inScheme G.

Step 1 4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acidmethyl ester

To a solution of 4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acidmethyl ester (0.183 g, 0.684 mmol) in DMF (5 mL) was added iodobenzene(0.15 g, 0.753 mmol), CuI (0.028 g, 0.137 mmol),(1S,2S)—N,N′-dimethylcyclohexane-1,2-diamine (0.04 g, 0.274 mmol), andCs₂CO₃ (0.15 g, 1.36 mmol). The reaction mixture was stirred at 110° C.overnight, then cooled to room temperature and partitioned between waterand ethyl acetate. The organic layer was separated, dried over MgSO₄,filtered and concentrated under reduced pressure. Purification of theresidue by column chromatography gave 0.12 g (53%) of445-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid methylester.

Step 2 4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid

4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid methylester was treated with NaOH using the procedure of step 3 of Example 1to afford 445-methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylicacid.

Step 3 4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide

4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid wasreacted with C-(5-methyl-pyrazin-2-yl)-methylamine in the presence ofEDCI, HOBt and NMM using the procedure of step 4 of Example 1 to provide4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide, MS (M+H)=435.

Similarly prepared, replacing C-(5-methyl-pyrazin-2-yl)-methylamine with(S)-2-amino-propan-1-ol, was4-(5-methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide, MS (M+H)=387.

Similarly prepared, replacing iodobenzene with 4-iodo-toluene, was4-(5-methyl-pyridin-2-yl)-1-p-tolyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide, MS (M+H)=449.

Additional compounds prepared using the above procedure are shown inTable 1.

Example 33-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide

The synthetic procedure used in this preparation is outlined below inScheme H.

Step 1 7-Iodo-3-isobutyl-3H-benzoimidazole-5-carboxylic acid methylester

To a solution of 7-iodo-3H-benzoimidazole-5-carboxylic acid methyl ester(783 mg, 2.59 mmol) in DMF (50 mL) was added Cs₂ ^(CO) ₃ (1.69 g, 5.18mmol), followed by isobutyl bromide ((0.338 mL, 3.11 mmol). The reactionmixture was stirred room temperature overnight, then partitioned betweenwater and ethyl acetate. The organic layer was separated, dried overMgSO₄, filtered and concentrated under reduced pressure. Purification ofthe residue by column chromatography gave 805 mg (87%) of7-iodo-3-isobutyl-3H-benzoimidazole-5-carboxylic acid methyl ester (theregioisomer 7-iodo-1-isobutyl-1H-benzoimidazole-5-carboxylic acid methylester (100 mg, 11%) was recovered as separate fraction).

Step 23-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acidmethyl ester

To a solution of 7-iodo-3-isobutyl-3H-benzoimidazole-5-carboxylic acidmethyl ester (400 mg, 1.12 mmol) in THF (4 mL) was added Pd(PPh₃)₄ (65mg, 0.056 mmol), followed by 5-methyl-pyridinyl zinc bromide (2.68 mL of0.5M solution in THF, 1.34 mmol). The reaction mixture was stirredovernight at room temperature, then quenched by addition of saturatedaqueous NH₄Cl solution. The mixture was partitioned between water andethyl acetate, and the organic layer was separated, dried over MgSO₄,filtered and concentrated under reduced pressure. Purification by columnchromatography gave 207 mg (57%) of3-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acidmethyl ester.

Step 33-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid

3-isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acidmethyl ester 207 mg, 0.64 mmol) was suspended in a mixture of methanol(10 mL) and water (2 mL). To this suspension was added LiOH (46 mg, 1.92mmol). The mixture was stirred overnight at room temperature, then madeacidic by addition of 1N aqueous HCl, and concentrated to dryness underreduced pressure. The residue was re-dissolved in methanol, filtered toremove insolubles, and the filtrate was concentrated under reducedpressure to provide 165 mg (84%) of3-isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylicacid.

Step 43-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid((5)-2-hydroxy-1-methyl-ethyl)-amide

To a solution of (g, 0 mmol) in a mixture of dichloromethane (2.5 mL)and DMF (2.5 mL) was added (S)-2-amino-propan-1-ol (0.17 mL, 0.22 mmol),EDCI (42 mg, 0.22 mmol), HOBt (30 mg, 0.22 mmol), and NMM (0.121 mL,1.10 mmol). The reaction mixture was stirred at room temperatureovernight, then partitioned between water and ethyl acetate. The organiclayer was separated, dried over MgSO₄, filtered and concentrated underreduced pressure. Purification of the residue by column chromatographygave 9 mg (11%) of3-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide, MS (M+H)=367.

Similarly prepared, replacing (S)-2-amino-propan-1-ol withC-(5-methyl-pyrazin-2-yl)-methylamine, was3-isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide, MS (M+H)=415.

Example 4 Formulations

Pharmaceutical preparations for delivery by various routes areformulated as shown in the following Tables. “Active ingredient” or“Active compound” as used in the Tables means one or more of theCompounds of Formula I.

Composition for Oral Administration

Ingredient % wt./wt. Active ingredient 20.0% Lactose 79.5% Magnesiumstearate 0.5%

The ingredients are mixed and dispensed into capsules containing about100 mg each; one capsule would approximate a total daily dosage.

Composition for Oral Administration

Ingredient % wt./wt. Active ingredient 20.0% Magnesium stearate 0.5%Crosscarmellose sodium 2.0% Lactose 76.5% PVP (polyvinylpyrrolidine)1.0%

The ingredients are combined and granulated using a solvent such asmethanol. The formulation is then dried and formed into tablets(containing about 20 mg of active compound) with an appropriate tabletmachine.

Composition for Oral Administration

Ingredient Amount Active compound 1.0 g Fumaric acid 0.5 g Sodiumchloride 2.0 g Methyl paraben 0.15 g Propyl paraben 0.05 g Granulatedsugar 25.5 g Sorbitol (70% solution) 12.85 g Veegum K (Vanderbilt Co.)1.0 g Flavoring 0.035 ml Colorings 0.5 mg Distilled water q.s. to 100 ml

The ingredients are mixed to form a suspension for oral administration.

Parenteral Formulation

Ingredient % wt./wt. Active ingredient 0.25 g Sodium Chloride qs to makeisotonic Water for injection  100 ml

The active ingredient is dissolved in a portion of the water forinjection. A sufficient quantity of sodium chloride is then added withstirring to make the solution isotonic. The solution is made up toweight with the remainder of the water for injection, filtered through a0.2 micron membrane filter and packaged under sterile conditions.

Suppository Formulation

Ingredient % wt./wt. Active ingredient 1.0% Polyethylene glycol 100074.5% Polyethylene glycol 4000 24.5%

The ingredients are melted together and mixed on a steam bath, andpoured into molds containing 2.5 g total weight.

Topical Formulation

Ingredients Grams Active compound 0.2-2 Span 60 2 Tween 60 2 Mineral oil5 Petrolatum 10 Methyl paraben 0.15 Propyl paraben 0.05 BHA (butylatedhydroxy anisole) 0.01 Water q.s. 100

All of the ingredients, except water, are combined and heated to about60° C. with stirring. A sufficient quantity of water at about 60° C. isthen added with vigorous stirring to emulsify the ingredients, and waterthen added q.s. about 100 g.

Nasal Spray Formulations

Several aqueous suspensions containing from about 0.025-0.5 percentactive compound are prepared as nasal spray formulations. Theformulations optionally contain inactive ingredients such as, forexample, microcrystalline cellulose, sodium carboxymethylcellulose,dextrose, and the like. Hydrochloric acid may be added to adjust pH. Thenasal spray formulations may be delivered via a nasal spray metered pumptypically delivering about 50-100 microliters of formulation peractuation. A typical dosing schedule is 2-4 sprays every 4-12 hours.

Example 5 P2X₃/P2X_(2/3) FLIPR (Fluorometric Imaging Plate Reader) Assay

CHO-K1 cells were transfected with cloned rat P2X₃ or human P2X_(2/3)receptor subunits and passaged in flasks. 18-24 hours before the FLIPRexperiment, cells were released from their flasks, centrifuged, andresuspended in nutrient medium at 2.5×10⁵ cells/ml. The cells werealiquoted into black-walled 96-well plates at a density of 50,000cells/well and incubated overnight in 5% CO₂ at 37° C. On the day of theexperiment, cells were washed in FLIPR buffer (calcium- andmagnesium-free Hank's balanced salt solution, 10 mM HEPES, 2 mM CaCl₂,2.5 mM probenecid; FB). Each well received 100 μl FB and 100 μl of thefluorescent dye Fluo-3 AM [2 μM final conc.]. After a 1 hour dye loadingincubation at 37° C., the cells were washed 4 times with FB, and a final75 μl/well FB was left in each well.

Test compounds (dissolved in DMSO at 10 mM and serially diluted with FB)or vehicle were added to each well (25 μl of a 4× solution) and allowedto equilibrate for 20 minutes at room temperature. The plates were thenplaced in the FLIPR and a baseline fluorescence measurement (excitationat 488 nm and emission at 510-570 nm) was obtained for 10 seconds beforea 100 μl/well agonist or vehicle addition. The agonist was a 2× solutionof α,β-meATP producing a final concentration of 1 μM (P2X₃) or 5 μM(P2X_(2/3)). Fluorescence was measured for an additional 2 minutes at 1second intervals after agonist addition. A final addition of ionomycin(5 μM, final concentration) was made to each well of the FLIPR testplate to establish cell viability and maximum fluorescence of dye-boundcytosolic calcium. Peak fluorescence in response to the addition ofα,β-meATP (in the absence and presence of test compounds) was measuredand inhibition curves generated using nonlinear regression. PPADS, astandard P2X antagonist, was used as a positive control.

Using the above procedure, compounds of the invention exhibited activityfor the P2X₃ and P2X_(2/3) receptors as shown in Table 1.

Example 6 In Vivo Assay for Asthma and Lung Function

BALb/cJ mice are immunized with a standard immunization protocol.Briefly, mice (N=8/group) are immunized i.p. with ovalbumin (OVA; 10 μg)in alum on days 0 and 14. Mice are then challenged with aerosolized OVA(5%) on day 21 and 22. Animals receive vehicle (p.o.) or a compound ofthe invention (100 mg/kg p.o.) all starting on day 20.

Lung function is evaluated on day 23 using the Buxco system to measurePenH in response to an aerosol methacholine challenge. Mice are theneuthanized and plasma samples collected at the end of the study.

Example 7 Volume Induced Bladder Contraction Assay

Female Sprague-Dawley rats (200-300 g) were anesthetized with urethane(1.5 g/kg, sc). The animals were tracheotomized, and a carotid arteryand femoral vein were cannulated for blood pressure measurement and drugadministration, respectively. A laparotomy was performed and the ureterswere ligated and transected proximal to the ligation. The externalurethral meatus was ligated with silk suture and the urinary bladder wascannulated via the dome for saline infusion and bladder pressuremeasurement.

Following a 15-30 minute stabilization period the bladder was infusedwith room temperature saline at 100 μl/min until continuousvolume-induced bladder contractions (VIBCs) were observed. The infusionrate was then lowered to 3-5 μl/min for 30 minutes before the bladderwas drained and allowed to rest for 30 minutes. All subsequent infusionswere performed as indicated except the lower infusion rate wasmaintained for only 15 minutes instead of 30 minutes. Bladder fillingand draining cycles were repeated until the threshold volumes (TV; thevolume needed to trigger the first micturition bladder contraction)varied by less than 10% for two consecutive baselines and contractionfrequency was within 2 contractions for a 10 minute period following theslower infusion rate. Once reproducible TVs and VIBCs were establishedthe bladder was drained and the animal was dosed with drug or vehicle(0.5 ml/kg, i.v.) 3 minutes prior to the start of the next scheduledinfusion.

Example 8 Formalin Pain Assay

Male Sprague Dawley rats (180-220 g) are placed in individual Plexiglascylinders and allowed to acclimate to the testing environment for 30min. Vehicle, drug or positive control (morphine 2 mg/kg) isadministered subcutaneously at 5 ml/kg. 15 min post dosing, formalin (5%in 50 μl) is injected into plantar surface of the right hind paw using a26-gauge needle. Rats are immediately put back to the observationchamber. Mirrors placed around the chamber allow unhindered observationof the formalin-injected paw. The duration of nociphensive behavior ofeach animal is recorded by a blinded observer using an automatedbehavioral timer. Hindpaw licking and shaking/lifting are recordedseparately in 5 min bin, for a total of 60 min. The sum of time spentlicking or shaking in seconds from time 0 to 5 min is considered theearly phase, whereas the late phase is taken as the sum of seconds spentlicking or shaking from 15 to 40 min. A plasma sample is collected.

Example 9 Colon Pain Assay

Adult male Sprague-Dawley rats (350-425 g; Harlan, Indianapolis, Ind.)are housed 1-2 per cage in an animal care facility. Rats are deeplyanesthetized with pentobarbital sodium (45 mg/kg) administeredintraperitoneally. Electrodes are placed and secured into the externaloblique musculature for electromyographic (EMG) recording. Electrodeleads are tunneled subcutaneously and exteriorized at the nape of theneck for future access. After surgery, rats are housed separately andallowed to recuperate for 4-5 days prior to testing.

The descending colon and rectum are distended by pressure-controlledinflation of a 7-8 cm-long flexible latex balloon tied around a flexibletube. The balloon is lubricated, inserted into the colon via the anus,and anchored by taping the balloon catheter to the base of the tail.Colorectal distension (CRD) is achieved by opening a solenoid gate to aconstant pressure air reservoir. Intracolonic pressure is controlled andcontinuously monitored by a pressure control device. Response isquantified as the visceromotor response (VMR), a contraction of theabdominal and hindlimb musculature. EMG activity produced by contractionof the external oblique musculature is quantified using Spike2 software(Cambridge Electronic Design). Each distension trial lasts 60 sec, andEMG activity is quantified for 20 sec before distension (baseline),during 20 sec distension, and 20 sec after distention. The increase intotal number of recorded counts during distension above baseline isdefined as the response. Stable baseline responses to CRD (10, 20, 40and 80 mmHg, 20 seconds, 4 minutes apart) are obtained in conscious,unsedated rats before any treatment.

Compounds are evaluated for effects on responses to colon distensioninitially in a model of acute visceral nociception and a model of colonhypersensitivity produced by intracolonic treatment with zymosan (1 mL,25 mg/mL) instilled into the colon with a gavage needle inserted to adepth of about 6 cm. Experimental groups will consist of 8 rats each.

Acute visceral nociception: For testing effects of drug on acutevisceral nociception, 1 of 3 doses of drug, vehicle or positive control(morphine, 2.5 mg/kg) are administered after baseline responses areestablished; responses to distension are followed over the next 60-90minutes.

Visceral hypersensitivity: For testing effects of drug or vehicle afterintracolonic treatment with zymosan, intracolonic treatment is givenafter baseline responses are established. Prior to drug testing at 4hours, responses to distension are assessed to establish the presence ofhypersensitivity. In zymosan-treated rats, administration of 1 of 3doses of drug, vehicle or positive control (morphine, 2.5 mg/kg) aregiven 4 hours after zymosan treatment and responses to distensionfollowed over the next 60-90 minutes.

Example 10 Cold Allodynia in Rats with a Chronic Constriction Injury ofthe Sciatic Nerve

The effects of compounds of this invention on cold allodynia aredetermined using the chronic constriction injury (CCI) model ofneuropathic pain in rats, where cold allodynia is measured in acold-water bath with a metal-plate floor and water at a depth of 1.5-2.0cm and a temperature of 3-4° C. (Gogas, K. R. et al., Analgesia, 1997,3, 1-8).

Specifically, CCI, rats are anesthetized; the trifurcation of thesciatic nerve is located and 4 ligatures (4-0, or 5-0 chromic gut) areplaced circumferentially around the sciatic nerve proximal to thetrifurcation. The rats are then allowed to recover from the surgery. Ondays 4-7 after surgery, the rats are initially assessed for cold-inducedallodynia by individually placing the animals in the cold-water bath andrecording the total lifts of the injured paw during a 1-min period oftime: The injured paw is lifted out of the water. Paw lifts associatedwith locomotion or body repositioning are not recorded. Rats thatdisplayed 5 lifts per min or more on day 4-7 following surgery areconsidered to exhibit cold allodynia and are used in subsequent studies.In the acute studies, vehicle, reference compound or compounds of thisinvention are administered subcutaneously (s.c.) 30 min before testing.The effects of repeated administration of the compounds of thisinvention on cold allodynia are determined 14, 20 or 38 h following thelast oral dose of the following regimen: oral (p.o.) administration ofvehicle, reference or a compound of this invention at ˜12 h intervals(BID) for 7 days.

Example 11 Cancer Bone Pain in C3H/HeJ Mice

The effects of compounds of this invention on bone pain are determinedbetween Day 7 to Day 18 following intramedullary injection of 2472sarcoma cells into the distal femur of C3H/HeJ mice.

Specifically, NCTC 2472 tumor cells (American Type Culture Collection,ATCC), previously shown to form lytic lesions in bone afterintramedullary injection, are grown and maintained according to ATCCrecommendations. Approximately 10⁵ cells are injected directly into themedullary cavity of the distal femur in anesthetized C3H/HeJ mice.Beginning on about Day 7, the mice are assessed for spontaneousnocifensive behaviors (flinching & guarding), palpation-evokednocifensive behaviors (flinching & guarding), forced ambultory guardingand limb use. The effects of compounds of this invention are determinedfollowing a single acute (s.c.) administration on Day 7-Day 15. Inaddition, the effects of repeated (BID) administration of compounds ofthis invention from Day 7-Day 15 are determined within 1 hour of thefirst dose on Days 7, 9, 11, 13 and 15.

While the present invention has been described with reference to thespecific embodiments thereof, it should be understood by those skilledin the art that various changes may be made and equivalents may besubstituted without departing from the true spirit and scope of theinvention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processstep or steps, to the objective spirit and scope of the presentinvention. All such modifications are intended to be within the scope ofthe claims appended hereto.

1. A compound of formula I:

or a pharmaceutically acceptable salt thereof, wherein: R¹ is:C₁₋₆alkyl; or halo; R² is: C₃₋₆cycloalkyl; C₁₋₆alkoxy-C₁₋₆alkyl;hydroxy-C₁₋₆alkyl; or heteroaryl-C₁₋₆alkyl; R³ is: C₁₋₆alkyl;hydroxy-C₁₋₆alkyl; C₁₋₆alkoxy-C₁₋₆alkyl; halo-C₁₋₆alkyl; C₃₋₆cycloalkyl;C₃₋₆cycloalkyl-C₁₋₆alkyl; phenyl optionally substituted with halo,C₁₋₆alkyl, C₁₋₆alkoxy or halo-C₁₋₆alkyl; or phenyl-C₁₋₆alkyl wherein thephenyl portion thereof is optionally substituted with halo, C₁₋₆alkyl,C₁₋₆alkoxy or halo-C₁₋₆alkyl; R⁴ and R⁵ each independently is: hydrogen;or fluoro; X is: N; or CR^(a) wherein R^(a) is C₁₋₆alkyl or halo; Y is:N; or CR^(b) wherein R^(b) is hydrogen or C₁₋₆alkyl; and Z is: N; orCRC; wherein R^(c) is hydrogen or C₁₋₆alkyl.
 2. The compound of claim 1,wherein R⁴ and R⁵ are hydrogen.
 3. The compound of claim 2, wherein R¹is methyl.
 4. The compound of claim 2, wherein R² is: cyclopropyl;2-methoxy-1-methyl-ethyl; 2-hydroxy-1-methyl-ethyl;5-methylpyrazin-2-yl-methyl; 1-pyrazin-2-yl-ethyl;pyrimidin-5-yl-methyl; 6-methyl-pyridazin-3-yl-methyl;pyridazin-3-yl-methyl; 5-methyl-pyrimidin-yl-methyl; or2-methyl-pyrimidin-5-yl-methyl.
 5. The compound of claim 2, wherein R²is 2-hydroxy-1-methyl-ethyl; 5-methylpyrazin-2-yl-methyl; or1-pyrazin-2-yl-ethyl.
 6. The compound of claim 2, wherein R³ isC₁₋₆alkyl; halo-C₁₋₆alkyl; phenyl optionally substituted with C₁₋₆alkyl;or phenyl-C₁₋₆alkyl wherein the phenyl portion thereof is optionallysubstituted with C₁₋₆alkyl.
 7. The compound of claim 2, wherein R³ isisopropyl, isobutyl, n-propyl, 3-methyl-butyl, 222-trifluoroethyl,2-methoxyethyl, phenyl, benzyl, 2-methyl-phenyl; 4-methyl-phenyl; or2-isopropyl-phenyl.
 8. The compound of claim 2, wherein R³ is isopropyl,isobutyl, n-propyl, or 3-methyl-butyl.
 9. The compound of claim 2,wherein R³ is phenyl, 2-methyl-phenyl; 4-methyl-phenyl; or2-isopropyl-phenyl.
 10. The compound of claim 2, wherein X is —N—. 11.The compound of claim 2, wherein X is —CR^(a)—.
 12. The compound ofclaim 11, wherein R^(a) is hydrogen or halo.
 13. The compound of claim2, wherein R^(a) is hydrogen.
 14. The compound of claim 2, wherein Y isN.
 15. The compound of claim 2, wherein Y is CR^(b).
 16. The compound ofclaim 2, wherein Z is N.
 17. The compound of claim 2, wherein Z isCR^(c).
 18. The compound of claim 1, wherein said compound is selectedfrom: 1-Isobutyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Butyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Butyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;1-(2-Methoxy-ethyl)-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide;1-(3-Methyl-butyl)-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide;1-(3-Methyl-butyl)-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid (6-methyl-pyridazin-3-ylmethyl)-amide;1-Benzyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Benzyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;1-Benzyl-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylic acid(6-methyl-pyridazin-3-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-(2,2,2-trifluoro-ethyl)-1H-indazole-6-carboxylicacid (5-methyl-pyrazin-2-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-(2,2,2-trifluoro-ethyl)-1H-indazole-6-carboxylicacid (6-methyl-pyridazin-3-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-p-tolyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-p-tolyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-o-tolyl-1H-indazole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-o-tolyl-1H-indazole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;1-(2-Isopropyl-phenyl)-4-(5-methyl-pyridin-2-yl)-1H-indazole-6-carboxylicacid ((S)-2-hydroxy-1-methyl-ethyl)-amide;1-Isobutyl-4-(5-methyl-pyridin-2-yl)-1H-indole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Isobutyl-4-(5-methyl-pyridin-2-yl)-1H-indole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;4-(5-Methyl-pyridin-2-yl)-1-phenyl-1H-indole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indole-6-carboxylic acid(6-methyl-pyridazin-3-ylmethyl)-amide;1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indole-6-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide;1-Isopropyl-4-(5-methyl-pyridin-2-yl)-1H-indole-6-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide;3-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid(5-methyl-pyrazin-2-ylmethyl)-amide; and3-Isobutyl-7-(5-methyl-pyridin-2-yl)-3H-benzoimidazole-5-carboxylic acid((S)-2-hydroxy-1-methyl-ethyl)-amide.
 19. A pharmaceutical compositioncomprising: (a) a pharmaceutically acceptable carrier; and (b) acompound of claim
 1. 20. A method for treating a pain condition selectedfrom inflammatory pain, surgical pain, visceral pain, dental pain,premenstrual pain, central pain, pain due to burns, migraine or clusterheadaches, nerve injury, neuritis, neuralgias, poisoning, ischemicinjury, interstitial cystitis, cancer pain, viral, parasitic orbacterial infection, post-traumatic injury, or pain associated withirritable bowel syndrome, said method comprising administering to asubject in need thereof an effective amount of a compound of claim 1.